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Discussion Starter · #1 ·
What is the typical inseam length that would benefit from 180mm crank arms? I’ve got 36.5 inch inseam using the wrench science method. I have always run standard 175mm crank arms, but curious if my pedaling efficiency would improve with 180mm. I’m looking to buy a new set of cranks for my Ventana Saltamontes on order.
 

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Up yer kilt!
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Depends

Most people will tell you that there is little advantage for a bike with full gearing (3x9) to adding "5 mm". The reality is that you add a lot more than 5 mm but that's another question altogether.

If you "push" in bigger gears, then longer cranks will give you more mechanical advantage, but in the case of people who "spin" then the longer cranks will cost you more "time" per revolution.
The question is, what kind of rider (climber) are you??

CA -
 

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depends

Good answer, charlie. Yeah. It all depends on if you push big gears or spin small gears. I switched from 170s on my old road bike to 175s on me new road bike (I have about the same inseam as you) but it actually slowed me down considerably at first because I was used to the small circle efficiency of the shorter cranks. But if you have a SS or like to push big gears (and who doesn't ;)) then longer may be better in the long run. Some SSers are going even longer than 180s - I saw a post where I guy had just put (i think) 190s!
 

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err, 27.5+
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For a geared bike I don't see too much advantage. As others have posted big gear mashers will benefit.

I have a 34" inseam and run 170mm on my dual suspension, 175mm on my road bike, and 180mm on my SS. The SS is the only one that I really notice the longer arms being an advantage.

One thing to consider is replacement. In the event of something breaking or stripping it is really nice to run 175mm so you can get a replacement or a temp at the closest shop. Especially handy if you are on vacation.
 

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Discussion Starter · #5 ·
Thanks for all of the well-thought advice. Sounds like I should stick with 175. I tend to use my gears and spin. I know that the Saltamontes has a fairly active suspension and those type of bike are typically more efficient while pedaling in the saddle. Thanks
 

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Klydesdale
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I have a 35" inseam and definitely prefer to spin smaller gears rather than mash big ones. But since I got my first 180mm cranks a couple of years ago won't go back to 175mm ones unless I absolutely have to. There's no doubt in my mind that the extra length enables my legs to generate more power because I'm able to spin higher gears than I ever have before.
 

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longer lever

I have a very short inseem yet I have run 180 cranks for 12 years now. I am more of a masher than a spinner but I wouldnt be without 180's.
try to ride someones bike to try them.
btw a freind has a shorter leg due to an auto injury and he runs a 170 on his long leg and a 165 on his short leg, seems to help him. I road his epic for about 200 ft and gave it back to him. it felt realy weird.
 

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i have 180mm cranks on 2 bikes...

and i have a 36in inseam, using the competitive cyclist fit test. i find that im able to use power more effectively with these than my 175mm xtr's. especially when approaching a climb. i hit the bottom of the climb with a lot more momentum which helps a ton on technical climbs.
 

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Discussion Starter · #9 ·
I did some research on Google and found the following website.

www.cranklength.info

Based on this website and others; it looks like I should seriously consider 180mm.

All my friends ride 175 mm. I will try to find a shop that will let me try 180s.
 

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personal preference

well it sounds like personal preference really comes into play here. I ran 180's for years, liked them, and broke lots of them. Race Face was good and warrantied all of them,but the 180 length was always an issue. I had to wait. On my last breakage I needed cranks asap so I had them send 175's. I have to say I prefer the shorter arms. Better for spinning and way less rock smashing.
 

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Mmm Good thread lads well done!!.
Im on 175 at the moment but i think i need 180s as im a big fella and spin it up to get up there,i just think the mechanics of it all means ill go for 180s at my next upgrade,As by the time ive ive gotten out of the seat to stand up im usually stopped!!! LOL!!
 

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Maybe 185s...

I have a 34 inseam and I run 185s. I believe that's the longest in Shimanos XT and XTR lengths, but it helps. You're going to see the biggest difference in your climbs. Especially the low grade ones. Steep climbs... not alot of advantage, shallow climbs... you will be able to power up to speed and maintain your ride much easier. If you can find a 190, that may be your better bet. Good luck.
 
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